Cavy, common name for several genera of rodents native to South America. Cavies include the common guinea pig, the yellow-toothed cavies, the rock cavies, and the Patagonian cavies (also known as hares or maras). Yellow-toothed cavies and rock cavies generally resemble guinea pigs, with coat and color variations. The Patagonian cavies look more like short-eared rabbits with very long legs, and measure about 45 to 75 cm (about 18 to 30 in) long. All cavies have three digits on their hind feet and four on their forefeet. Most of them are crepuscular (active during the morning and evening) plant-eaters that dig burrows and live in large groups.

Scientific classification: Cavies make up the family Caviidae. Guinea pigs are classified in the genus Cavia. The yellow-toothed cavies make up the genus Galea, and the rock cavies make up the genus Kerodon. Patagonian cavies make up the genus Dolichotis.